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https://github.com/versity/scoutfs.git
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7a565a69df
Add percpu counters that will let us track all manner of things.
To report them we add a sysfs directory full of attribute files in a
sysfs dir for each mount:
# (cd /sys/fs/scoutfs/loop0/counters && grep . *)
skip_delete:0
skip_insert:3218
skip_lookup:8439
skip_next:1190
skip_search:156
The implementation is careful to define each counter in only one place.
We don't have to make sure that a bunch of defintions and arrays are in
sync.
This builds off of Ben's initial patches that added sysfs dirs.
Signed-off-by: Zach Brown <zab@versity.com>
Signed-off-by: Ben McClelland <ben.mcclelland@versity.com>
132 lines
3.5 KiB
C
132 lines
3.5 KiB
C
/*
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* Copyright (C) 2016 Versity Software, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/percpu_counter.h>
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#include "super.h"
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#include "counters.h"
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/*
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* Maintain simple percpu counters which are always ticking. sysfs
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* makes this a whole lot more noisy than it needs to be.
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*/
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#undef EXPAND_COUNTER
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#define EXPAND_COUNTER(which) { .name = __stringify(which), .mode = 0644 },
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static struct attribute scoutfs_counter_attrs[] = {
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EXPAND_EACH_COUNTER
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};
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/* zero BSS and + 1 makes this null terminated */
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#define NR_ATTRS ARRAY_SIZE(scoutfs_counter_attrs)
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static struct attribute *scoutfs_counter_attr_ptrs[NR_ATTRS + 1];
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static ssize_t scoutfs_counter_attr_show(struct kobject *kobj,
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struct attribute *attr, char *buf)
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{
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struct scoutfs_counters *counters;
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struct percpu_counter *pcpu;
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size_t index;
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/* use the index in the _attrs array to discover the pcpu pointer */
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counters = container_of(kobj, struct scoutfs_counters, kobj);
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index = attr - scoutfs_counter_attrs;
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pcpu = &counters->FIRST_COUNTER + index;
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return snprintf(buf, PAGE_SIZE, "%lld\n", percpu_counter_sum(pcpu));
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}
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static void scoutfs_counters_kobj_release(struct kobject *kobj)
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{
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struct scoutfs_counters *counters;
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counters = container_of(kobj, struct scoutfs_counters, kobj);
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complete(&counters->comp);
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}
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static const struct sysfs_ops scoutfs_counter_attr_ops = {
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.show = scoutfs_counter_attr_show,
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};
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static struct kobj_type scoutfs_counters_ktype = {
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.default_attrs = scoutfs_counter_attr_ptrs,
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.sysfs_ops = &scoutfs_counter_attr_ops,
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.release = scoutfs_counters_kobj_release,
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};
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int scoutfs_setup_counters(struct super_block *sb)
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{
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struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
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struct scoutfs_counters *counters;
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struct percpu_counter *pcpu;
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int ret;
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counters = kzalloc(sizeof(struct scoutfs_counters), GFP_KERNEL);
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if (!counters)
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return -ENOMEM;
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sbi->counters = counters;
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scoutfs_foreach_counter(sb, pcpu) {
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ret = percpu_counter_init(pcpu, 0, GFP_KERNEL);
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if (ret)
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return ret;
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}
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counters->kobj.kset = sbi->kset;
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init_completion(&counters->comp);
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ret = kobject_init_and_add(&counters->kobj, &scoutfs_counters_ktype,
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NULL, "counters");
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if (ret) {
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/* tear down partial to avoid destroying null kobjs */
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scoutfs_foreach_counter(sb, pcpu)
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percpu_counter_destroy(pcpu);
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kfree(counters);
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sbi->counters = NULL;
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}
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return ret;
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}
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void scoutfs_destroy_counters(struct super_block *sb)
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{
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struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
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struct scoutfs_counters *counters = sbi->counters;
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struct percpu_counter *pcpu;
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/* this only destroys fully initialized counters */
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if (!counters)
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return;
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kobject_del(&counters->kobj);
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kobject_put(&counters->kobj);
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wait_for_completion(&counters->comp);
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scoutfs_foreach_counter(sb, pcpu)
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percpu_counter_destroy(pcpu);
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kfree(counters);
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sbi->counters = NULL;
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}
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void __init scoutfs_init_counters(void)
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{
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int i;
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/* not ARRAY_SIZE because that would clobber null term */
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for (i = 0; i < NR_ATTRS; i++)
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scoutfs_counter_attr_ptrs[i] = &scoutfs_counter_attrs[i];
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}
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